Arnold xlarwasser



. 1,600,339 A. KLARWASSER PIPE annum& momma y Filed June 24, 1925 [n ren fa Arna!! r ;Vlarwsser Patented Sept 21 1926.

UNITED STATES 1,600,339 PATENT OFFICE.

ABNOLD KLARWASSER, OF COLOGNE, GERMANY, ASSIGNOR TO CLIMAX.- WIERZKE A. G.

. AM ES KENBERG, OF AACHEN 'PRUSSIA, GERMANY.

IPIPE-BENDING MACHINE.

' Application filed .Tune 24, 1925, Serial No. 39,346, -and in Germany .Tune 26..-1924.

This invention relates to a machine for manufacturing pipe-bends of the kind comprising a Stationary form, a 'revoluble pipev bending member and a supporting mandrel movable in the work in conformity with the working movement.

In the methods and machines of the kind .known hitherto, the supporting mandrel follows accurately the movement of the revolving pipe-bending member. The ,cylindrical portion of the mandrel always extends for a certain distance rearwardly beyond the point of contact between the pipebending member and the .pipe, This is necessary in order to L5 render the mandrel effective' and prevent the same from becoming worn out rapidly which would be the case if the mandrel would act on the inner surface of the pipe-wall only along a circular line. The portion of the 'mandrel referred to is indicated in the drawing by shading.' As the supporting mandrel thus has ,to act on the pipe-wall by a relativelj long cylindrical surface, a jamming .action is always produced between the mandrel' and the pipe-wall. This jamming is without anypermanent influence at the beginning and in the course of the bending operation, but it entails an outward bulging of the pipe as soon as the bending member and the supporting mandrel come to a standstill at the end of the bending operation.

The invention has for its object toobviate V the said disadvantage, this object being attained by providing the machine with means ;5 for imparting to the mandrel a lead with respect to the pipe-bending member shortly before the bending of the .pipe is terminated so that the bending of the last portion of the beud takes place without the action of the L0 supporting mandrel. In the new machine it is possible to define the lead of the m'andrel with relation to the revoluble pipe-bending member in. such a manner that also in thelast part of the bend- 15 ing operation there is neither produced an outward nor an inward bulging. The bend will therefore have a smooth curvature throughout. r\

Another'object of the invention resides in providin means for returning thesupport i ing man rel always exactly into its initial osition inspite of the lead imparted to it 111 the last part of the bending operation. The advantages of the present machine re- 'side in the possibility of relievingthe manthe invention is illustrated in the drel of the bending pressure at the end of the bending operation and returning 'it automatically into its initial position as well as in the great accuracy of adjustment obtain# able without any special expenditure of Work and time and entirely independent from *the skill of the workman. i

An embodiment of the subject-matter o accompanying drawing in which:

Fig.`l is a plan view, partly in section of the pipe-bending machine at the beginning of thebending operation, and

Fig. 2 is a similar View of the machine after the bending operation has been termi-' nated. v

- The machine essentially consists of a s`ta-. tionary form b and of a pipe-bending member 0 Wl1lCl1 lS adjustably fastened on a frame d. Theform b is of a circular shape and the frame d with the member cis adapted to revolve around the axis of the form b. The frame d rests on a Stationary base plate e which has an annular guiding groove f in which a stop g is adjustably fastened. The

frame ol has a yokelike extension k provided with a bore h' in which is guided a rod i which is connected with a bent arm la. The

?rod z' and arm k are connected at m with the supporting mandrel Z. A tension spring n is connected by one end to the frame d and by its other end to a nose v 'of the arm Jc. The latter has a guiding slot p which' is engaged by a guide pin p' fastened to the frame cl. Mounted for rotation on the frame d is a double-armed lever q having arms of different lengths. The movement of the long arm of the lever 'g is limited on the one hand by the arm k and on the other hand by a stop 7' on the frame ci, while its short bent arm terminates in front of a nose' s of the frame d. Screwed on the rod i are nuts t further rotary movement -of' the frame d causes a rotation of the lever q in` such a manner that its long arm moves the rods k, m, z' and the mandrel l with relation to the frame d and the pipe-bending member 0, contrary to the action of the spring n. Owing to this movement the mandrel has imparted to it a lead with respect to the. member cshortlybefore the bending operation is terminated, so that the supporting end of the mandrel is already in the straight section of 'the pipe a and thus relieved of the bending 10 .pressure while the last part of the bending operation is still being executed., As the bending of the last portion of the 'pipe-bend is, in this way, effectedwithout the' action of the mandrel which has been drawn out of the range .of the bending pressure, a visible bulging which otherwise occurs in the bending of thin-walled pipes, is positively avoided.

After loosening the holder w the pipe' a can be easily withdrawn from the machine and acted upon by the bending member 0, is.

drawn or elongated. If no supporting mani drel is used in the interior of the pipe, the

said elongating action will, of coursegproduce to a certain extent an inward bulging of the outer pipe wall. The mandrel therefore serves to'compensate this inward bul ing by roducing an outward bulging. The outwar bulgingtaused bythe mandrel is positive and somewhat stronger than the inward bulging due to the elongation, The outwardbulging therefore outweighs the inward bulging.' According to the size of the pipes, this outward bulging ranges betweenfractions of a millimeter insmall tubes and 'about 2 millimeters in .large tubes. This, slight outward bulging is of no importance' in the curved portion (bend) ofthe pipe because it is uniform throughout 'the bend, but it would leave, a visible disturbant protuberance or outward bulging at the point where the curved portion of the pipe passes into the straight portion, if the mandrel would` be allowed to remain in action during the very last step of the bending operation. In order to avoid this visibledisturbant outward bulging at the end of the benttportion, the mandrel is automaticallydrawn' out of the range of the bending pressure during the last part of the bending operatiang. The result thereof is that in this last part of the bending operation without mandrel the elon ation of the outer pipe wall compensates t e ou'tward bulgingand produces a gradual and smooth transition from the curved portion to the straight portion of the pipe.

It will be clear from the foregoingr that the lead is imparted to the mandrel'at the end `of the bending operation for preventing the formation of a visible disturbant outward bulging or pretuberance at the end of the bend and for allowing the continued' bending operation to produce a smooth transition from the curved or bentportion to the straight portion.

Having thus described my invention, what I claim as new and desire to secure by Letters-Patent, is

1. In a pipe-bending machine, comprising in combination a Stationary form, a revoluble pipe-bending member and a supporting mandrel movable in the work in conformity with the working movement, an automatically operating stop mechanism for imparting to the supporting mandrel a lead with relation to the pipe-bending member shortly before the bending operation terminated. 2. In a pipe-bending machine, comprising in combination, a base plate, a Stationary form, a frame mounted for rotation around the axis ofthe formon the base plate, a pipe bending member carried by and movable with the said frame and a supporting mandrel likewise carried by the said frame and movable with relation to the latter and in the work during the bending operation, a stop member adjustably fixed on the base plate, a double-armed lever" mounted for swinging motion on the frame, one arm of this lever being held in contact with' the mandrel and the other arm of the lever being adapted to strike against the said stop member of thebaseplate shortly before the rotary movement of -the frame' and bending member is terminated and 'to be rocked by the said stop member so as to cause the firstsaid arm of the lever to impart to the. man: drel a lead with relation to'the pipe-bending member, and stops on the frame forlimiting the swinging movement of the lever.

' 3. In a pipe-bending machine, comprising in combination, a base 'plate, a Stationary. form, a frame mounted for rotation around the axis of the form on the base plate, a'

pipe-bending member carried by and' 'movable with the said frame and a supporting.'

mandrel likewise carried by the said frame and movable with relation to "the latter and in the work during the' bendingoperation,

a stop .member adjustably fixed on the base plate, a double-armed lever mounted for swinging motion on the frame, one armofthis lever being held in contact with the mandrel and the other arm' of the lever being adapted to strike againstthe said stop member ofthe base plate shortly before the rotarymovement of theframeand bending u initial positions when the pipe-bending member is returned into its initial position, 10 stops for limiting the swinging movement of the lever and stops for limiting the movement of the mandrel with relation to the frame.

In testimony whereof I have signed my 15 name to this specification.'

ARNOLD KLARWASSER. 

